Casting generally uses a mold containing a cavity (and a core if necessary) usually made of molding sand. The mold is provided with a pouring cup, a sprue, a runner, and a gate for pouring a molten metal into the cavity (hereinafter, also collectively referred to as a gating system), which are formed so as to lead to the cavity. The mold is further provided with a vent connecting with the outside and a riser or flow off, which are generally made of molding sand together with the mold in a common shape. In some cases, the pouring system is built with a fire-resistant material such as a ceramic tube. There have been proposed methods for casting with a mold having a runner that is a structure containing organic and inorganic fibers and a binder, as described in JP-A2007-21578 and the like. JP-A 2007-21578 describes a structure for casting, that contains organic and inorganic fibers and a binder and is coated with inorganic particles to reduce gas defects in cast steel. JP-A2008-142755 discloses a structure for casting, that has a metal-coated surface with vanadium or the like. JP-A 2009-195982 discloses a structure for casting, that contains at least one kind of inorganic particles selected from amorphous graphite and artificial graphite, inorganic fibers, and a thermosetting resin, and has the gas permeability of 1 to 500. JP-A 08-257673 describes application of a slurry containing a zirconium powder, water, and a silica sol containing silicic anhydride to the surface of a mold. JP-A2010-142840 discloses a structure for casting, that is coated on the surface with a coating liquid composition containing flake graphite and a water-soluble binder containing gum arabic, a phenol resin or aluminium phosphate.